I could not access the links you provided using ANSYS 17.1 and 18.1. So, I had to wait until the Christmas holidays finished to solve some IT issues to install ANSYS 19.1 and now I'm able to access these links.After reading the links along with the fluent user's guide manual, the definition of a new transport equation can be by setting the parameters for the unsteady, convection, diffusion and source terms. To do that, a single UDF file should be written and contains the following DEFINE_DIFFUSIVITY, DEFINE_UDS_FLUX, DEFINE_UDS_UNSTEADY and DEFINE_SOURCE. Is this right or there are some other techniques?Also, I read in some forums that the UDS equation is laminar by default which means I have to include the turbulence effects in the diffusion term. Is this right? Thank you.n